Busbar assembly for an electrified vehicle and method of forming the same

ABSTRACT

A battery assembly according to a non-limiting aspect of the present disclosure includes, among other things, an array of battery cells, with each cell including a terminal, and a busbar assembly having a first busbar component and a second busbar component. Further, each of the terminals are electrically coupled to both the first busbar component and the second busbar component. A method of forming a busbar assembly is also disclosed.

RELATED APPLICATIONS

This application is a divisional of prior U.S. application Ser. No.15/461,104, filed Mar. 16, 2017, the entirety of which is hereinincorporated by reference.

BACKGROUND

This disclosure relates to a busbar assembly for an electrified vehicle,and also relates to a method of forming the busbar assembly.

The need to reduce automotive fuel consumption and emissions is wellknown. Therefore, vehicles are being developed that reduce or completelyeliminate reliance on internal combustion engines. Electrified vehiclesare one type of vehicle being developed for this purpose. In general,electrified vehicles differ from conventional motor vehicles becausethey are selectively driven by battery powered electric machines.Conventional motor vehicles, by contrast, rely exclusively on aninternal combustion engine to propel the vehicle.

Electrified vehicles include one or more high voltage batteryassemblies, each of which includes a number of battery cells. Thevarious cells are connected by a plurality of busbars. Specifically, thebusbars are used to carry current from the terminals of one cell toanother. Typically, a one-piece busbar is used to connect the terminalsof a plurality of cells.

SUMMARY

A battery assembly according to a non-limiting aspect of the presentdisclosure includes, among other things, an array of battery cells, witheach cell including a terminal, and a busbar assembly having a firstbusbar component and a second busbar component. Further, each of theterminals are electrically coupled to both the first busbar componentand the second busbar component.

In a further non-limiting embodiment of the foregoing battery assembly,each terminal is electrically coupled to a tab, and each tab isconnected to both the first busbar component and the second busbarcomponent.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, each of the first busbar component and the second busbarcomponent includes a carrier and a plurality of feeders projecting fromthe carrier.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, each feeder of the first busbar component is connected to acorresponding feeder of the second busbar component by a respective oneof the tabs.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, the tabs are welded to the feeders of the first busbarcomponent and the second busbar component.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, the feeders of the first busbar component are spaced-apartfrom the feeders of the second busbar component.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, the carriers of the first and second busbar components areparallel to one another.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, the feeders of the first and second busbar componentsproject substantially perpendicular from a respective carrier.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, the feeders of the first and second busbar components aresubstantially aligned with one another relative to a length of thebattery assembly.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, each of the tabs project outwardly from a side of the arrayof battery cells.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, each of the tabs are moveable between a straight positionand a folded position, and each tab connects the first busbar componentto the second busbar component when in the folded position.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, the tabs project through windows between adjacent feederswhen in the straight position.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, the busbar assembly includes an electrical input and anelectrical output, one of the electrical input and electrical outputbeing on the first busbar component and the other of the electricalinput and electrical output being on the second busbar component.

In a further non-limiting embodiment of any of the foregoing batteryassemblies, the assembly further comprises a frame configured to holdthe first busbar component and the second busbar component relative tothe battery array, the frame having a base and cantilevered armsprojecting from the base.

A method of making a busbar assembly according to a non-limiting aspectof the present disclosure includes, among other things, forming a firstbusbar component and a second busbar component from a blank of material.

In a further non-limiting embodiment of the foregoing method, the firstbusbar component and the second busbar component are formed using asingle cutting process.

In a further non-limiting embodiment of any of the foregoing methods,the forming step includes cutting the blank of material beginning at afirst perimeter edge of the blank and ending at a second perimeter edgeof the blank opposite the first perimeter edge.

In a further non-limiting embodiment of any of the foregoing methods,the forming step includes cutting a serpentine pattern in the blankbetween the first perimeter edge and the second perimeter edge.

In a further non-limiting embodiment of any of the foregoing methods,the serpentine pattern includes a plurality of perpendicular turns.

In a further non-limiting embodiment of any of the foregoing methods,the first busbar component is substantially the same size and shape asthe second busbar component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a powertrain of an electrified vehicle.

FIG. 2 schematically illustrates a battery assembly of an electrifiedvehicle.

FIG. 3 illustrates an example busbar assembly including a first busbarcomponent and a second busbar component.

FIG. 4 is a cross-sectional view of an example frame for attaching thebusbar assembly to a battery array.

FIG. 5 illustrates the example busbar assembly arranged relative to aplurality of tabs.

FIG. 6 illustrates a blank of material from which the busbar assembly isformed, in one example.

FIG. 7 illustrates the blank of raw material and an example cuttingpath.

FIG. 8 illustrates the blank of raw material after a cutting process iscomplete.

FIG. 9 is a side-by-side comparison of a busbar formed using a knownprocess relative to the disclosed process.

DETAILED DESCRIPTION

This disclosure relates to a busbar assembly for an electrified vehicle,and also relates to a method of forming the busbar assembly. In thisdisclosure, the busbar assembly has a first busbar component and asecond busbar component. When the busbar assembly is used in a batteryassembly, the terminals of a plurality of battery cells are electricallycoupled to both the first busbar component and the second busbarcomponent. Among other benefits, the disclosed busbar assembly is formedin a way that significantly reduces material waste relative to the priorart, which in turn reduces cost. These and other features are discussedin greater detail in the following paragraphs of this detaileddescription.

FIG. 1 schematically illustrates a powertrain 10 for an electrifiedvehicle 12. Although depicted as a hybrid electric vehicle (HEV), itshould be understood that the concepts described herein are not limitedto HEV's and could extend to other electrified vehicles, including, butnot limited to, plug-in hybrid electric vehicles (PHEV's) and batteryelectric vehicles (BEV's).

In one embodiment, the powertrain 10 is a power-split powertrain systemthat employs a first drive system and a second drive system. The firstdrive system includes a combination of an engine 14 and a generator 18(i.e., a first electric machine). The second drive system includes atleast a motor 22 (i.e., a second electric machine), the generator 18,and a battery assembly 24. In this example, the second drive system isconsidered an electric drive system of the powertrain 10. The first andsecond drive systems generate torque to drive one or more sets ofvehicle drive wheels 28 of the electrified vehicle 12. Although apower-split configuration is shown, this disclosure extends to anyhybrid or electric vehicle including full hybrids, parallel hybrids,series hybrids, mild hybrids or micro hybrids.

The engine 14, which in one embodiment is an internal combustion engine,and the generator 18 may be connected through a power transfer unit 30,such as a planetary gear set. Of course, other types of power transferunits, including other gear sets and transmissions, may be used toconnect the engine 14 to the generator 18. In one non-limitingembodiment, the power transfer unit 30 is a planetary gear set thatincludes a ring gear 32, a sun gear 34, and a carrier assembly 36.

The generator 18 can be driven by the engine 14 through the powertransfer unit 30 to convert kinetic energy to electrical energy. Thegenerator 18 can alternatively function as a motor to convert electricalenergy into kinetic energy, thereby outputting torque to a shaft 38connected to the power transfer unit 30. Because the generator 18 isoperatively connected to the engine 14, the speed of the engine 14 canbe controlled by the generator 18.

The ring gear 32 of the power transfer unit 30 may be connected to ashaft 40, which is connected to vehicle drive wheels 28 through a secondpower transfer unit 44. The second power transfer unit 44 may include agear set having a plurality of gears 46. Other power transfer units mayalso be suitable. The gears 46 transfer torque from the engine 14 to adifferential 48 to ultimately provide traction to the vehicle drivewheels 28. The differential 48 may include a plurality of gears thatenable the transfer of torque to the vehicle drive wheels 28. In oneembodiment, the second power transfer unit 44 is mechanically coupled toan axle 50 through the differential 48 to distribute torque to thevehicle drive wheels 28.

The motor 22 can also be employed to drive the vehicle drive wheels 28by outputting torque to a shaft 52 that is also connected to the secondpower transfer unit 44. In one embodiment, the motor 22 and thegenerator 18 cooperate as part of a regenerative braking system in whichboth the motor 22 and the generator 18 can be employed as motors tooutput torque. For example, the motor 22 and the generator 18 can eachoutput electrical power to the battery assembly 24.

The battery assembly 24 is an exemplary electrified vehicle battery. Thebattery assembly 24 may be a high voltage traction battery pack thatincludes a plurality of battery assemblies 25 (i.e., battery arrays orgroupings of battery cells) capable of outputting electrical power tooperate the motor 22, the generator 18 and/or other electrical loads ofthe electrified vehicle 12. Other types of energy storage devices and/oroutput devices can also be used to electrically power the electrifiedvehicle 12.

In one non-limiting embodiment, the electrified vehicle 12 has two basicoperating modes. The electrified vehicle 12 may operate in an ElectricVehicle (EV) mode where the motor 22 is used (generally withoutassistance from the engine 14) for vehicle propulsion, thereby depletingthe battery assembly 24 state of charge up to its maximum allowabledischarging rate under certain driving patterns/cycles. The EV mode isan example of a charge depleting mode of operation for the electrifiedvehicle 12. During EV mode, the state of charge of the battery assembly24 may increase in some circumstances, for example due to a period ofregenerative braking. The engine 14 is generally OFF under a default EVmode but could be operated as necessary based on a vehicle system stateor as permitted by the operator.

The electrified vehicle 12 may additionally operate in a Hybrid (HEV)mode in which the engine 14 and the motor 22 are both used for vehiclepropulsion. The HEV mode is an example of a charge sustaining mode ofoperation for the electrified vehicle 12. During the HEV mode, theelectrified vehicle 12 may reduce the motor 22 propulsion usage in orderto maintain the state of charge of the battery assembly 24 at a constantor approximately constant level by increasing the engine 14 propulsionusage. The electrified vehicle 12 may be operated in other operatingmodes in addition to the EV and HEV modes within the scope of thisdisclosure.

FIG. 2 illustrates a battery assembly 54 that can be incorporated intoan electrified vehicle. For example, the battery assembly 54 could beemployed within the electrified vehicle 12 of FIG. 1 . The batteryassembly 54 includes one or more battery arrays, which can be describedas groupings of battery cells, for supplying electrical power to variousvehicle components. In this example the battery assembly 54 includes asingle battery array 56. However, it should be understood that batteryassembly 54 could include multiple battery arrays.

The battery array 56 includes a plurality of battery cells 58 that arestacked side-by-side along a length L of the battery array 56. In oneembodiment, the battery cells 58 are prismatic, lithium-ion cells.However, battery cells having other geometries (cylindrical, pouch,etc.) and/or other chemistries (nickel-metal hydride, lead-acid, etc.)could alternatively be utilized within the scope of this disclosure.

The battery array 56 can be arranged to connect the battery cells 58 ina desired manner. In one example, certain of the battery cells 58 areconnected in parallel, while certain others are connected in series. Inother examples, all of the battery cells 58 are connected in parallel.

In this disclosure, the battery cells 58 are connected using busbarassemblies. Busbar assemblies carry current from one battery cell 58 toanother. In particular, the battery cells 58 each include two electricalterminals—a positive terminal and a negative terminal—which areconnectable using busbar assemblies. In this disclosure, the batterycells 58 each include at least one tab 60 projecting from a side of thebattery array 56. In one particular example, the battery cells 58 eachinclude two tabs 60 projecting from opposite sides of the battery array56, with one tab electrically coupled to a negative terminal of the celland the other tab electrically coupled to the positive terminal of thecell. In this regard, the tabs 60 may be part of the battery cells 58,and can be referred to as cell tabs. In other examples, each tab 60 maybe connected to similarly-charged terminals (e.g., both negative, orboth positive) of more than one cell.

FIG. 3 illustrates an example busbar assembly 62 according to thisdisclosure. For ease of reference, FIG. 3 illustrates the busbarassembly 62 as it would be mounted to the side of the battery array 56,in one example, without illustrating the detail of the battery array 56.The length L and height H directions of the battery array 56 are shownin FIG. 3 for reference. It should be understood that one or more busbarassemblies 62 may be mounted to each side of the battery array 56,depending on the particular application.

The busbar assembly 62 includes a first busbar component 64 and a secondbusbar component 66. In use, terminals of a plurality of battery cells58 are electrically coupled to both the first and second busbarcomponents 64, 66. The first and second busbar components 64, 66 aremade of a conductive material, such as copper or other suitableconductive materials like bi-metals, and are capable of carrying currentfrom the battery cells 58 and distributing the same throughout thebattery array 56.

With continued reference to FIG. 3 , the first busbar component 64includes a carrier 68 and a plurality of feeders 70 projecting from thecarrier 68. The second busbar component 66, in this example, is sizedand shaped substantially the same as the first busbar component 64, andalso includes a carrier 72 and a plurality of feeders 74 projecting fromthe carrier 72. In this example, the first and second busbar components64, 66 are intended to be identically sized, however the term “sized andshaped substantially the same” is used in this particular respect toaccount for manufacturing inaccuracies. Further, in this example, thereare six feeders 70, 74 projecting from the carriers 68, 72, but itshould be understood that the amount of feeders can vary depending onthe battery array configuration and number of battery cells 58.

In one example, the carriers 68, 72 extend along a side of the batteryarray 56 in a direction parallel to the length L of the battery array56. The carriers 68, 72 have a length L₁ and a width W₁ (only labeledrelative to carrier 68). When mounted to the battery array 56, thelength L₁ is parallel to the length L.

The feeders 70, 74 project from a respective carrier 68, 72 by a lengthL₂, and each feeder 70, 74 has a width W₂ (only labeled relative to oneof the feeders 70). The feeders 70, 74 are equally spaced-apart from oneanother, and in this example are each spaced-apart from one another by awidth W₃. In this example, the width W₃ is substantially equal to thewidth W₂. When mounted to the battery array 56, the first and secondbusbar components 64, 66 are arranged such that the feeders 70, 74 faceone another, and such that the feeders 70, 74 are substantially alignedrelative to the length L of the battery array 56.

In one example, the carrier 68 of the first busbar component 64 ispositioned above the tabs 60, relative to the height H of the batteryarray, in a first location 76 (FIG. 2 ), and the carrier 72 of thesecond busbar component 66 is positioned below the tabs 60 in a secondlocation 78 (FIG. 2 ). In this way, the carriers 68, 72 of the first andsecond busbar components 64, 66 are parallel to one another. The alignedfeeders 70, 74 define windows 80 between adjacent feeders 70, 74. Thewindows 80 have a width W₃ and a length substantially equal to twice L₂.In this example, the ends 82, 84 of the feeders 70, 74 are spaced-apartfrom one another by a relatively small gap such that current will notflow between the feeders 70, 74 until connected by a tab 60. As will bediscussed below, the windows 80 allow for attachment of the tabs 60 tothe busbar assembly 62.

In one example, the first and second busbar components 64, 66 aremounted to the side of the battery array 56 by a frame. FIG. 4 is across-sectional view of one example frame 86. In this example, the frame86 includes a base 88 and cantilevered arms 90 projecting from oppositesides of the base 88. The frame 86 includes a recess 92 between thecantilevered arms 90. A width of the cantilevered arms 90 is thickestaway from the base 88, such that the recess 92 is widest adjacent thebase 88. In use, one of the first or second busbar components 64, 66 ispushed against the cantilevered arms 90, which urges the cantileveredarms 90 away from one another. The busbar component then rests againstthe base 88 at the widest part of the recess 92. When the busbarcomponent is against the base 88, the cantilevered arms 90 are biasedback toward one another and maintain the position of the busbarcomponent. While FIG. 4 illustrates one example type of connectiveframe, it should be understood that other types of connections comewithin the scope of this disclosure.

FIG. 5 illustrates the manner in which the first and second busbarcomponents 64, 66 may be mechanically and electrically coupled to thebattery cells 58. In FIG. 5 , the first and second busbar components 64,66 are arranged in the same way as in FIG. 3 . FIG. 5 shows, on aschematic level, the first and second busbar components 64, 66 as theywould be arranged on the side of the battery array 56, and in particularshows the tabs 60 projecting through the windows 80.

In this example, each of the tabs 60 are moveable, and are in particularbendable, between a straight position and a folded position. In FIG. 5 ,there are four tabs 60 projecting through respective windows in astraight position, and one tab 60A that has been folded to a foldedposition. In the folded position, the tab 60A is in direct contact withboth the first busbar component 64 and the second busbar component 66.In particular, the tab 60A is in direct contact with one of the feeders70 and a corresponding one of the feeders 74. To affix the tab 60A tothe busbar assembly 62, in one example the tab 60A is welded to thefeeders 70, 74. A weld is represented at 94 in FIG. 5 . While only onetab 60A is in the folded position in FIG. 5 , each of the tabs 60 wouldbe folded and affixed to respective ones of the feeders 70, 74 in asimilar manner. While welding is mentioned herein, it should beunderstood that other attachment techniques come within the scope ofthis disclosure.

When all tabs are connected to corresponding feeders 70, 74, the currentfrom the battery cells 58 is distributed throughout the battery array.In one example, the busbar assembly 62 includes an electrical input 96and an electrical output 98. In this example, the electrical input 96 ison the first busbar component 64, and the electrical output 98 is on thesecond busbar component 66, although the opposite could be true.Further, in another arrangement, the electrical input and output 96, 98could be provided on the same one of the first or second busbarcomponent 64, 66. In any case, the electrical input and output 96, 98are used to electrically couple the busbar assembly 62 to other busbarassemblies within the battery array 56, for example, depending on theparticular application. Additionally, the electrical input 96 could be amain electrical input for the battery cell, meaning the input would beon the most positive or negative portion of the array. Likewise, theelectrical output 98 could be a main electrical output for the batterycell. In other examples where there is more than one busbar assembly 62on each side of the battery array, the electrical input and output 96,98 are intermediate inputs and outputs.

In this disclosure, the busbar assembly 62 is a two-piece assembly andconsists only of the first busbar component 64 and the second busbarcomponent 66. By providing the busbar assembly 62 as a two-pieceassembly, ease of manufacture is increased and material waste issignificantly reduced relative to prior techniques. The reduction inmaterial waste will be appreciated with reference to the method offorming the busbar assembly 62, which will now be described.

Another aspect of this disclosure relates to a method of making a busbarassembly having a first busbar component and a second busbar componentfrom a blank of raw material. In one particular example, the first andsecond busbar components are formed using a single cutting step.

FIG. 6 illustrates an example blank 100 of material for forming thebusbar assembly 62. In one example, the blank 100 is a single piece ofconductive material, such as copper, although other conductive materialscan be used. In this example, the blank 100 is rectangular. The blank100 has a width X and a height Y. In one example, the width X is equalto L₂ plus twice W₁, and the height Y is equal to L₁ plus W₂.

With reference to FIG. 7 , the first and second busbar components 64, 66are formed by cutting the blank 100 beginning at a first perimeter edge102 of the blank and ending at a second perimeter edge 104 of the blankopposite the first perimeter edge 102. In this example, a cutting pathis illustrated at 106. The blank 100 is cut along the cutting path 106using a laser-cutting process in one example, although it should beunderstood that other manufacturing processes come within the scope ofthis disclosure.

In this example, the cutting path 106 is generally a serpentine patternbetween the first perimeter edge 102 and the second perimeter edge 104.The serpentine pattern corresponds to the shape of the first and secondbusbar components 64, 66 (labeled in FIG. 7 for reference). Theserpentine pattern allows the first and second busbar components 64, 66to be formed from a single blank 100 of material by a single cuttingstep.

The cutting path 106 in this example includes a plurality ofperpendicular turns (e.g., ninety-degree turns). In one particularexample, the cutting path 106 begins at the first perimeter edge 102 andinitially extends into the blank 100 in a first direction perpendicularto the first perimeter edge 102 by a distance equal to W₂, asrepresented at line segment 106A. The cutting path 106 then takes aperpendicular turn and travels in a second direction by a distance equalto L₂, as represented at line segment 106B. The cutting path 106 thenmakes a perpendicular turn back to the first direction and travels adistance equal to W₂, as represented at line segment 106C. The cuttingpath then makes another perpendicular turn and travels in a thirddirection opposite the second direction by a distance equal to L₂, asrepresented at line segment 106D. The cutting path 106 continues in thismanner until it reaches the second perimeter edge 104.

By following the cutting path 106 shown in FIG. 7 , material waste issignificantly reduced, and in particular there is no wasted materialbetween the feeders 70, 74. For instance, the only waste when followingthe cutting path 106 of FIG. 7 are two relatively small pieces 108, 110.The pieces 108, 110 have a length equal to W₁ and a width equal to W₂.After removing the pieces 108, 110, the result of the cutting process isshown in FIG. 8 .

FIG. 9 is a to-scale comparison of a known one-piece busbar, which isformed using an existing technique, relative to the busbar assemblyformed using the disclosed process. An example known busbar is shown at112. The busbar 112 has a width X₁ and a height Y. The height Y is aboutthe same as the height of the blank 100 of the present disclosure, butthe width X₁ is about twice as large as the width X of the blank 100.Thus, the busbar 112 is formed using a substantially larger piece ofmaterial than the disclosed busbar assembly 62.

Further, the busbar 112 is formed from a single piece of material byremoving windows 114 from the center of the material. The windows 114are thus labeled as “wasted material” in FIG. 9 . On the other hand, thepieces 108, 110 (labeled “waste” for reference in FIG. 9 ) are the onlywasted material in the disclosed process, and the pieces 108, 110 arerelatively small compared to the windows 114. Note that the windows 114are sized substantially the same as the windows 80, whereas the pieces108, 110 are much smaller.

Accordingly, by providing a multi-piece busbar assembly (e.g., atwo-piece busbar assembly) as opposed to a one-piece busbar, not only isthe present busbar assembly 62 formed from a much smaller blank ofmaterial to begin with, but less of that blank is wasted duringmanufacturing. Thus, the present disclosure provides significant costsavings relative to the prior art.

It should be understood that terms such as “about,” “substantially,” and“generally” are not intended to be boundaryless terms, and should beinterpreted consistent with the way one skilled in the art wouldinterpret those terms.

Although the different examples have the specific components shown inthe illustrations, embodiments of this disclosure are not limited tothose particular combinations. It is possible to use some of thecomponents or features from one of the examples in combination withfeatures or components from another one of the examples.

One of ordinary skill in this art would understand that theabove-described embodiments are exemplary and non-limiting. That is,modifications of this disclosure would come within the scope of theclaims. Accordingly, the following claims should be studied to determinetheir true scope and content.

The invention claimed is:
 1. A method of making a battery assembly,comprising: forming a first busbar component and a second busbarcomponent from a blank of material; attaching the first busbar componentand the second busbar component to an array of battery cells, whereineach cell in the array includes a terminal, and wherein each terminal isconnected to both the first busbar component and the second busbarcomponent.
 2. The method of making the battery assembly as recited inclaim 1, wherein each terminal is electrically coupled to a tab, andwherein the attaching step includes connecting each tab to both thefirst busbar component and the second busbar component.
 3. The method ofmaking the battery assembly as recited in claim 2, wherein the attachingstep includes welding each tab to both the first busbar component andthe second busbar component.
 4. The method of making the batteryassembly as recited in claim 2, wherein: each of the first busbarcomponent and the second busbar component includes a carrier and aplurality of feeders projecting from the carrier, and the attaching stepincludes connecting each tab directly to a respective feeder of thefirst busbar component and a corresponding feeder of the second busbarcomponent.
 5. The method of making the battery assembly as recited inclaim 4, wherein each of the tabs contacting the first busbar componentand the second busbar component are connected to a similarly-chargedterminal.